The oil pans used with many internal combustion engines are generally made of a thin walled material. The sump portion of such a thin wall oil pan usually has a drain opening therein. Since walls of the pan are thin, a reinforcing member is usually attached around the drain opening and has a threaded hole therein. A plug having a seal or gasket thereon is screwed into the reinforcing member and the gasket seals against the thin wall of the pan. An example of such a drain mechanism is disclosed in U.S. Pat. No. 3,754,677 issued to Karl Hug on Aug. 28, 1973. For example, a threaded plug having a flat seal thereon is screwed into a threaded nut. As the plug is tighten in the nut the flat seal is brought into sealing contact with the thin wall of the container or pan and seals. The drain plug and seal combinations of this configuration have several major drawbacks: if the plug is over tightened the threads may be stripped, or the gasket may be damaged and failure of the seal can occur, and if the plug is undertightened the joint can leak.
Another example of a drain plug assembly is disclosed in U.S. Pat. No. 3,079,663 issued to Robert M. Buchwald on Jul. 16, 1963. This patent discloses a thin walled oil pan having a drain plug located within the sump portion of the oil pan. The configuration includes a flared port in the pan and a drain plug assembly. The drain plug assembly is constructed of a perforated support member secured to the inside of the sump portion and positioned concentric to the drain port. The support member has a valve or drain plug member threadedly mounted therein. The drain plug has an O-ring seal retained therein. As the drain plug is unscrewed from the support member, the O-ring comes into contact with the flared portion of the flared port and seals thereon. In this configuration, if an excess torque is applied to the drain plug the area around the flared port can bend. The results of the bent or deflected surface can result in the seal not seating and leakage can occur. Another disadvantage of this configuration is that if an excess torque is applied to the drain plug, the support member is forced or pushed away from the pan to which it is mounted, thus, highly stressing the connection therebetween. The continued flexing of the joint can cause failure of the joint or the metal therearound resulting in leakage. Another drawback to the internally positioned drain plug occurs as the O-ring is unseated. The hot oil escapes as soon as the O-ring is unseated and continues to spill onto the individual's hand or tool as the drain passage is continued to be opened. Thus, the added aggravation and unnecessary cleanup compounds the undesirable use of the above described drain plug configuration. A further drawback exists when the O-ring seal becomes damaged and a replacement seal is needed. The ability to replace the above seal is nearly impossible.
The present invention is directed to overcoming one or more of the problems as set forth above.